Behavior of faulty double BJT BiCMOS logic gates

Logic Behavior of a Double BJT BiCMOS device under transistor level shorts and opens is examined. In addition to delay faults, faults that cause the gate to exhibit sequential behavior were observed. Several faults can be detected only by monitoring the current. The faulty behavior of Bipolar (TTL) and CMOS logic families is compared with BiCMOS, to bring out the testability differences.